package com.wc.AlgoOJ_train.train3_算法大礼包.c3_贪心.AG0412_生态化反;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

/**
 * @Author congege
 * @Description
 * @Date Created in 2024/1/30-22:40
 * http://43.138.190.70:8888/p/AG0412
 */
public class Main {
    static FastReader sc = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);
    static int N = 110;
    static int n;
    static PriorityQueue<Double> q = new PriorityQueue<>(Comparator.reverseOrder());

    public static void main(String[] args) {
        n = sc.nextInt();
        while (n-- > 0) {
            q.add(sc.nextDouble());
        }
        while (q.size() >= 2) {
            double d1 = q.poll();
            double d2 = q.poll();
            q.add(0.5 * Math.sqrt(d1 * d2));
        }

        out.println(q.poll());
        out.flush();
    }
}

class FastReader {
    StringTokenizer st;
    BufferedReader br;

    FastReader() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String nextLine() {
        String s = "";
        try {
            s = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return s;
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    boolean hasNext() {
        while (st == null || !st.hasMoreElements()) {
            String s = nextLine();
            if (s == null) {
                return false;
            }
            st = new StringTokenizer(s);
        }

        return true;
    }
}